Conventionally, software distribution systems have been provided that allow electronic data distributed in the form of a CD-ROM purchased by the user to be downloaded to the user's (client) terminal, in other words, a personal computer. In such systems, various technologies have been suggested to prevent unauthorized use of distributed data by users who have not purchased the CD-ROM.
For example, pages 8 to 12 and FIG. 2 of JP 2002-132365 A (hereinafter referred to as patent document 1) discloses an electronic data distribution management system (electronic data distribution management unit) in which “authentication code”, “software type”, and “amount” are transmitted to a software management server from a web server when “user specific information” and “software request information” are transmitted to the web server from the client terminal. Then, an e-mail with an attachment file containing software embedded with authentication code management module is sent to a mail server. Thereafter, when the client terminal attempts to retrieve e-mails from the mail server, the e-mail with the attachment file is sent to the client terminal from the mail server. Thus, even if unauthorized third person who did not purchase the electronic data acquires the software, in other words, the electronic data, such user will not be able to use the software despite acquisition of valid authentication code since encryption code is arranged to vary depending on when data encryption was executed.
A control program that prevents unauthorized copying of software products is disclosed in pages 7 to 9 and FIG. 2 of JP 2002-258963 A (hereinafter referred to as patent document 2). The disclosed control program generates user ID and password for entering online shopping sites to unauthorized users as well. Authorized users are allowed to shop or utilize other services by using the credit awarded as authorized user privileges. However, if an authorized user allows an unauthorized user to use his/her credit, the authorized user who is the original proprietor of such privileges is penalized by being denied further use of the credit.
As described earlier, patent document 1 discloses a technology that prevents unauthorized use in an electronic data distribution management system in which electronic data requested by the client terminal is sent to the client terminal from the server; whereas patent document 2 discloses a technology that prevents unauthorized use in a control program for preventing unauthorized copy of software products in which the authorized user him/herself is psychologically pressured so as not to allow unauthorized use by penalizing the authorized user for permission of unauthorized use.
Nowadays, sewing systems have been suggested in which terminals are connected to various types of sewing machines and sewing operation is executed by sending sewing data to the sewing machines from the terminals. The same approach is employed when updating the version of the control program used in controlling the drive of the sewing machine. To describe specifically, an update control program provided in the form of a CD-ROM is transmitted to the sewing machine from the terminal to render the program update to take place in the sewing machine.
In such case, the technologies disclosed in patent documents 1 and 2 for preventing unauthorized use are ineffective in preventing unauthorized execution of the update control program on the sewing machine. Thus, it is not possible to prevent unauthorized third-party use of the update control program provided in the form of a CD-ROM. This becomes a significant risk factor especially when the update program is not free of charge. In such instances, the developer of the update control program will not be able to collect its expense.